1. Field of the Invention
This invention relates to a flat battery for use in a micro-size device such as a wristwatch, handy measuring or caluculating instruments and so on.
2. Prior Art
The construction of the conventional battery cell of this type consist of a cup-shaped anode can, a cap-shaped cathode can and a gasket provided between the anode and cathode cans. An anode active substance, an electrolyte, a cathode active substance and a separator are contained in such cell construction.
The sealing structure of the conventional battery above mentioned is performed by establishing close pressing contiguity among the gasket, the anode and cathode cans through use of the compressive counterforce of the gasket in which it is deformed. Therefore, it is necessary to obtain a large compressive counterforce by increasing the thickness of the gasket. However, by increasing the thickness of the gasket, the volume which is occupied by the gasket is increased, for this reason, the size of the battery becomes enlarged, or the net capacity of the cell diminishes. Otherwise, it is necessary to reduce the thickness of the plates constituting the anode and cathode cans for increasing the discharge capacity in the same size cell. Furthermore, when the compressive force of the gasket is enlarged in order to ensure the leakproof property, the internal pressure of the battery cell increases, this lead to one of the causes of leakage.